反应详情

95.7 g of finely pulverised aluminium chloride are suspended in 180 ml of absolute methylene chloride. While stirring and cooling, 35 g of 5-methoxybenzocyclobutene-1-carboxylic acid methyl ester, dissolved in a small amount of methylene chloride, are added dropwise in such a manner that the temperature remains below 30°. At the same temperature, 50.5 g of benzoyl chloride are added dropwise thereto and the whole is subsequently heated at reflux for 4 hours. After cooling, the reaction mixture is poured onto 600 g of ice. The organic phase is separated off and the aqueous phase is extracted 3 times with 150 ml of methylene chloride each time. The combined organic phases are washed once with 250 ml of water, dried over magnesium sulphate and concentrated by evaporation. The excess benzoyl chloride is distilled off under a high vacuum and the residue is crystallised from ether/petroleum ether. 4-benzoyl-5-hydroxybenzocyclobutene-1-carboxylic acid methyl ester is obtained in the form of yellow crystals having a melting point of 75°-76°.

1. temperaturecooling
2. additionare added dropwise in such a manner that the temperature
3. customremains below 30°
4. temperaturethe whole is subsequently heated
5. temperatureat reflux for 4 hours
6. temperatureAfter cooling
7. customThe organic phase is separated off
8. extractionthe aqueous phase is extracted 3 times with 150 ml of methylene chloride each time
9. washThe combined organic phases are washed once with 250 ml of water
10. dry with materialdried over magnesium sulphate
11. concentrationconcentrated by evaporation
12. distillationThe excess benzoyl chloride is distilled off under a high vacuum
13. customthe residue is crystallised from ether/petroleum ether